Sam Winchester's Big Brother is Helplessly in Love
by ButterflyInAJar
Summary: On one of their routine hunts, Sam walks in on Cas and Dean. Completely blindsided(and mentally scarred), Sam tries to understand how his brother is sleeping with and angel while ignoring the images running through his head. Dean talks with him about "feelings." Set in Season 8. Also posted on my Ao3 account (thisismypseudonym)
Sam rubbed his temple and tried to focus on breathing. He prayed that in a few moments he would wake up wrapped in his motel sheets with the realization this was just a nightmare. However, a few minutes passed, and Sam was still cowering at the bar of a small diner. It was real. Some of the locals were starting to give him weird looks because he'd been staring at his beer for ten minutes. Or maybe it was twenty.

Sure, he'd had his awkward encounters with Dean's…hookups. He'd walked in on Dean and a girl more times than he could count, and he was used to finding socks on the door handle. Or, god forbid, Dean got drunk enough and brought a girl back to their room while Sam was happily researching on the bed (He thought Dean did that just to watch Sam try to scramble to the bathroom or the Impala before clothes started coming off). It was inevitable when they shared the same bedroom every night.

But this…this was different. No, different didn't even begin to describe it. There didn't seem to be a word in Sam's extensive vocabulary that described the situation. Only one phrase entered his mind.

 _What. The. Actual. Fuck._

—

Everything had been pretty normal. Four days ago, Sam, Dean, and Cas left the bunker to check on a case in Missouri. Six young females had turned up dead in the last three months, but local police had no leads on their killer. Just like Sam suspected, it was a ghost.

The ghost herself wasn't that powerful, but she was good at hiding. It had taken them four days to put the pieces of puzzle together and figure out ghost was haunting girls who resembled her. The ghost put up a fight, but they'd managed to escape with minor cuts and bruises. They decided to stay overnight in the neighboring town so they wouldn't have to drive through the night.

The only thing that was odd about the entire trip was that Cas hadn't vanished once the case was over. In fact, he rode in the Impala for the entire trip and even stayed with them in the motel room. He only left once Sam not so subtly implied it would be better if Cas returned in the morning when they would actually be awake. Cas looked upset, but Sam brushed it off as usual Cas weirdness.

That's why he wasn't fazed when he went grocery shopping, but Cas and Dean elected to stay behind and watch a movie. He grumbled a bit about Dean's laziness and promised he would return in an hour or so. Nothing out of the ordinary.

As it turns out, the grocery store was closed, and the diner didn't have take out. He tried to call Dean, but the phone went straight to voicemail. _Typical Dean,_ Sam thought, _He better not complain when I return empty handed._ A dissatisfied Sam returned to the motel no more than 15 minutes after he left.

Had Sam known what happened next, he would have gotten back into the Impala and drove as far away as he could get. But, because the universe apparently hated Sam Winchester, he blissfully walked straight into maybe the most disturbing image a little brother can see.

Cas was sprawled out across the carpet while a shirtless Dean straddled his lap and sucked on his neck. Then, before Sam could move, Dean was attempting to shove his tongue as far down Cas's throat as possible. In all of Sam's existence, he had never once heard the noises currently coming out of Dean's mouth.

What happened next is a blur. Dean started reaching for Cas's zipper, Sam might have screamed, and the room key was lost in the chaos. All he can clearly remember is sprinting from the motel room to the nearest establishment that served alcohol.

—

The blonde waitress kindly asked Sam if he wanted a different drink, but all Sam could do was groan. Thankfully, she took the hint and left him alone. He didn't think any amount of beer could wipe his memory.

It didn't matter that Cas was a dude, or his vessel was a dude, whatever. If being with guys made Dean happy, Sam didn't care. He didn't care if Dean was into guys and girls. Sam went to school in California for god's sake.

The issue Sam had was, it was Cas. Cas! The guy who stabbed them in the back and saved their lives! The fucking angel of the lord! Cas! _Oh god,_ Sam thought, _Cas!_

Cas was family. The entire thing was basically incest! His brother was committing incest!

"Can I please have a beer?" A deep voice said.

Speak of the devil.

"You realize you could have driven here right?" Dean said, "I know you're worried about keeping your girlish figure, but-"

"Dean-"

"You haven't touched your beer. Don't tell me you've signed an abstinence pledge or some shit."

"Dean!" Sam squeaked, "We need to talk about what I just saw."

"No we don't, Sammy."

The waitress passed by Dean and put down a cold beer bottle.

"Yes we do Dean," Sam lowered his voice, "You and Cas-"

"What happens between me and Cas is none of your business."

"You're sleeping together, Dean! Cas is our partner and our best friend! He's family. I can't just ignore this."

"You can, and you will."

Sam sighed. He should have known it would be impossible to have this conversation with his emotional constipated brother. Fuck Dean's issues with emotions. This conversation was happening here and now.

"When did it start?" Sam quietly asked.

Dean paused and took a sip of his beer. Sam stayed silent in hopes Dean would answer if Sam just gave him time.

"Purgatory," Dean said, "Purgatory changed everything."

Sam couldn't help but laugh. "Are you telling me, between fighting vampires and werewolves, you found the time to hook up with Cas?"

"God Sammy—no it's —why do you have to say it like that? That's not what it is," Dean blushed.

"Oh my god," Sam said, "You're in love with him aren't you? Dean, you're in love with Cas. Like, you love him."

"Shut your face!"

"Dean, I don't care if you're gay or whatever-"

"See, this is why I didn't tell you. You don't get it. I'm not even remotely attracted to guys," Dean paused, "I don't want any girl or guy. I just want Cas. He's it for me, man."

Sam paused. There was still one question he was itching to ask before he threw confetti at the happy couple…and proceeded to book another room

"Does he feel the same way?" He asked.

Dean's entire face lit up like a Christmas tree. "That's the best part. Cas is all mine, Sammy. Forever."

How did Sam miss this? How could he possibly miss his big brother falling helplessly in love? All the signs were right there in front of him; the lingering looks and the 'profound bond'. For god's sake, Chuck's creepy fan girls had seen it years ago.

Sam knew he should say something heartfelt (since that was probably the sweetest sentence that would ever come out of Dean's mouth), but nothing came up. Despite his best efforts, Sam was still having trouble forcing down the image of Dean attempting to eat Cas's face. It didn't help that Sam could distinctively see a purple bruise poking out of Dean's shirt collar.

"I'm happy for you. Honest. Just, can you please warn me if I'm about to walk in on…that?"

"No promises."

—

Sam was extremely satisfied with the outcome of the conversation. The ride back to the motel was light and teasing. Sam didn't even flinch when a certain dark haired angel appeared behind Dean and lightly kissed him on the cheek. He thought it was even kind of cute.

At least until Sam was woken up in the middle of the night by a creaking bed and loud panting.

Author's Note

I personally believe there aren't enough fanfics out there with Sam not knowing anything about Destiel, so I wrote this. I've also posted this story on my Ao3 account(thisismypseudonym). I apologize for the spelling mistakes. My only editor is Word. Please comment and like.


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